Ideally, the evolution of the scaled model is similar to that of the original but on a much more convenient timescale (e.g. Koyi, 1997 Ranalli, 2001 Graveleau et al., 2012, and references therein). In Earth sciences, scaled models have been employed for over a century to test hypotheses on the driving mechanisms of tectonic processes derived from, and constrained by, a variety of geological and geophysical data (e.g. (a) Preprocessed image at time t with illuminated particles (b) images at time t and t+Δ t are split into small interrogation windows (here 128 pixels), and the interrogation windows are cross-correlated (c) correlation yields a map, indicating how well the interrogation windows correlate with each other when shifted along x and y axes of the image space (here interrogation windows were 32 pixels wide) (d) the peak of the correlation map is precisely (i.e. The more complete characterisation of the deformation of tectonic analogue models will facilitate the comparison with numerical simulations and geological data and help produce conceptual mechanical models.įigure 1Principles of PIV. The presented software package allows producing these finite strain measures while also accessing incremental measures of strain. The finite strain has long been the only quantified measure of strain in analogue models. The deformation gradient tensor is calculated from the deformed state and decomposed into the finite rigid-body rotation and left or right finite-stretch tensors, allowing the deformation ellipsoids to be drawn. We benchmark the measures of finite displacements using specific synthetic tests for each summation mode. The incremental displacements can then be summed up with Eulerian or Lagrangian summation, and the components of the 2-D finite strain tensor can be calculated together with the finite principal strain and maximum finite shear. We illustrate with synthetic images how the algorithm produces maps of the velocity gradients, small-strain tensor components, incremental or instantaneous principal strains and maximum shear. Here, we demonstrate, using a new version of our software package (TecPIV), how the correlation of successive time-lapse images of a deforming model allows not only to evaluate the components of the strain-rate tensor at any time in the model but also to calculate the finite displacements and finite strain tensor. Image correlation techniques have provided new ways to analyse the distribution of deformation in analogue models of tectonics in space and time.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |